Diaminoalkanediylidenetetraphosphonic acids useful in cleaning compositions

ABSTRACT

CLEANSING COMPOSITIONS ARE DESCRIBED CONTAINING A SYNTHETIC ORGANIC DETERGENT AND AS A BUILDER THEREFOR A DIAMINOALKANEDIYLIDENETETRAPHOSPHONIC ACID.

United States Patent O US. Cl. 260502.5 3 Claims ABSTRACT OF THEDISCLOSURE Cleansing compositions are described containing a syntheticorganic detergent and as a builder therefor adiaminoalkanediylidenetetraphosphonic acid.

BACKGROUND OF THE INVENTION (A) Field of the invention This inventionrelates to cleansing compositions and in particular to detergentcompositions having builder ingredients for augmenting the cleansingaction of the detergent.

(B) Description of the prior art In the cleansing art it is well-knownthat the efficacy of soap or detergent is considerably improved by thepresence of certain supplementary substances commonly referred to asbuilders. While the benefits derived from such entities are widelyappreciated, the mechanism by which they increase detergency has neverbeen fully elucidated. Very likely several phenomena come into playthereby greatly complicating the formulation of any single theory toaccount for the behavior of builders. This is lent credence when it isrealized that detergency itself is highly complex in nature involvingmany factors. Among those believed to have some effect on builtdetergency systems are stabilization of solid soil, emulsification ofsoil particles, the surface activity of the aqueous detergent solution,solubilization of water insoluble materials, foaming or suds formingcharacteristics of the washing solution, peptization of soilagglomerates, neutralization of acid soil and sequestration of mineralhardening constituents present in the washing solution. Other less welldefined and understood factors also may exert some influence. Since nogeneral rule is known which enables one to predict Whether a particularsubstance is capable of performing as an overall detergency builder,resort must be had to a great deal of empirical testing andinvestigation of candidate materials.

Among the known builders, representatives may be found which are of theorganic and inorganic types. Examples of the latter are thewater-soluble inorganic alkaline salts as typified by alkali metalcarbonates, borates, phosphates, polyphosphates, bicarbonates, silicatesand the like. Examples of the former are alkali metal, ammonium andsubstituted ammonium aminopolycarboxylates as represented by sodium andpotassium ethylenediaminetetraacetate, sodium and potassiumN-(2-hydroxyethy1)- ethylenediaminetriacetate, sodium and potassiumnitrilotriacetate, sodium, potassium and triethanolammonium-N- PatentedFeb. 23, 1971 ice (Z-hydroxyethyl)nitrilodiacetate as well as the alkalimetal salts of phytic acid, e.gt, sodium or potassium phytate, etc.

Although generally satisfactory, the builder materials utilizedheretofore suffer from certain limitations and disadvantages. Even themost widely accepted group of builder materials, the so-called condensedinorganic polyphosphates such as the alkali metal tripolyphosphates, arenot without their shortcomings. Such compounds, the most common of whichis sodium tripolyphosphate, exhibit a propensity when used in detergentcompositions, of hydrolyzing into less condensed derivatives havingdiminished builder properties. In fact these less condensed products,which include orthoand pyro-phosphates, may form undesirableprecipitates in the aqueous washing solution.

As the need for detergent builders has grown and expanded, moreattention is being given to the development of new and improved membersof this class of cleanser adjuncts.

SUMMARY OF THE INVENTION It has now been discovered that excellentbuilder characteristics can be realized by the use of certainorgano-phosphorus acids collectively referred to asdiaminoalkanediylidene-tetraphosphonic acids wherein two phosphonogroups and one amino group are attached to each terminal carbon atom ofthe alkanediylidene, and the provision of cleansing compositionscontaining them in combination with a water-soluble non-soap syntheticdetergent surfactant as well as the preparation and use of suchcompositions constitutes the principal object and purpose of theinvention. Other objects and purposes will become apparent in theensuing description.

DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENTS Thediaminoalkanediylidenetetraphosphonic acid builder materials herein canbe depicted by the following general formula wherein A is a 2-6 carbonalkylene bridge which may be centrally interrupted by oxygen or sulfurand R is a hydrogen or lower hydroxyalkyl such as HOCH HOCH CHHO(|JHCH2-, HOCH-CH, etc.

CH3 CH3 CH3 As understood herein a lower hydroxyalkyl means that thehydrocarbon moiety may contain from l-S carbon atoms.

As can be seen from an inspection of the formula, the builder materialsof the present invention have a molecular structure in which twophosphono groups and one amino group are attached to the terminal carbonatoms of a saturated hydrocarbon bridge optionally interrupted by sulfuror oxygen. According to Chemical Abstracts, a saturated hydrocarbonbridge having two unsatisfied valences on each of its terminal carbonatoms is referred to as an alkanediylidene radical and can beillustrated by the formula Where the connecting alkanediylidene bridgecontains no interrupting oxygen or sulfur atoms, the resulting compoundsare known chemical entities and are described in the technicalliterature. They are obtained by reacting phosphorus trihalides withorganic nitriles. The reaction is carried out at temperatures betweenabout C. and 100 C. using about two moles of phosphorus trihalide permole of the nitrile. Either during or after the reaction, an organicacid, such as glacial acetic acid or oxygen-containing inorganic acidsuch as phosphorus acid, are added. After this treatment, the product ishydrolyzed with water to generate the free acids; or the monoordi-esters are produced by reaction with suitable alcohols or phenols,preferably in the presence of acid-binding agents. A detaileddescription of these organophosphorus compounds, including theirpreparation, is given in British Pat. No. 995,462.

Certain of the compounds falling within the ambit of Formula I have notbeen previously described and these can be represented by the followingconfiguration:

RNR RNR wherein R has the significance as above set forth, and n is aninteger of 1-3. These patentably new entities can be realized bycondensing a phosphorus trihalide, orthophosphorous acid and a bis(terminally substituted cyano-alkyl) sulfide or ether. After the initialexothermic reaction had subsided, a slightly elevated temperature wasmaintained for a time interval sufficient to complete the reaction.After hydrolyzing, the products were isolated in the form of whitesolids. They may be purified by dissolving in a base and reprecipitatedby acidification.

The builder materials herein are all hexabasic acids having a total of 8protons, two of which are held by the amino groups, thereby forminginner salts. The pK values of the fifth and sixth protons ranged from5.7, for the six carbon chain, and 5.9 for the seven carbon chain.However when an oxygen or sulfur atom is interposed in the alkylenechain, the pK values are 9.1 and 9.4 respectively. Thus, thetetraphosphonic acids containing an interrupting hetero atom in thealkylene bridge, provide buffering in a region which is particularlydesirable for detergent builder applications. Thus our newdiaminoalkanediylidenetetraphosphonic acids, containing an inter.-rupting hetero atom, constitute a sub-class which are more effectivedetergent builders than the general category of this type oforganophosphorus acids.

Among the detergent surfactant compounds, whose cleansing power isenhanced by the diaminoalkanediylidenetetraphosphonic acids of theinvention are the following categories and examples:

(1) Anionic Synthetic Detergents.These may be designated asWater-soluble salts of organic sulfuric reaction products having intheir molecular structure an alkyl or acyl radical of carbon atomcontent within the range of about 8 to about 18 in a sulfonic acid orsulfuric acid ester radical. Included are sodium or potassium alkylbenzene sulfonate in which the alkyl group contains about 9 to aboutcarbon atoms in either a straight chain or a branched chain; sodium andpotassium alkyl glyceryl ether sulfonates, especially those ethers ofhigher fatty alcohols derived from the reduction of coconut oil; thereaction product of higher fatty acids with sodium or potassiumisothionate, where, for example, the fatty acids are derived fromcoconut oil; sodium or potassium alkyl sulfonates and sulfatesespecially those alkyl sulfates derived by the sulfation of coconut ortallow fatty alcohols and mixtures of such alkyl sulfates, dialkylesters of sodium or potassium salts of sulfosuccinic acid, for example,the dihexyl ester; sodium and potassium salts of sulfated or sulfonatedmonoglycerides derived, for example, from coconut oil, sodium orpotassium salts of the higher fatty alcohol esters of sulfo-carboxylicacids, for example, the sodium salt of the lauryl alcohol ester ofsulfo-acetie acid; sodium or potassium salts of a higher fatty acidamide of methyl taurine in which the higher acyl radicals, for example,are derived from coconut oil; and others known in the art, a numberbeing specifically set forth in U.S. Pat. 2,486,921, issued to Byerly onNov. 1, 1949. Examples of other useful anionic non-soap syntheticdetergents are acyl sarcosinates, e.g., sodium N-lauroyl sarcosinate.

(2) Nonionic Non-Soap Synthetic Dete-rgents. These may be broadlyclassed as being constituted of a watersolubilizing polyoxyethylenegroup in chemical combination with an organic hydrophobic compound suchas polyoxypropylene, alkyl phenol, the reaction product of an excess ofpropylene oxide and ethylenediamine, and aliphatic alcohols. Thenonionic synthetic detergents have a molecular weight in the range offrom about 800 to about 11,000.

One well-known class of nonionic detergents is made available on themarket under the trade name of Pluronic. These compounds are formed bycondensing ethylene oxide with a hydrophobic base formed by thecondensation of propylene oxide with propylene glycol. The molecularweight of the hydrophobic base is of the order of 1,500 to 1,800. Theaddition of polyoxyethylene radicals to this hydrophobic base increasesthe water solubility of the entire molecule. Liquid products areobtained up to the point where the polyoxyethylene content is about 50%of the total weight of the condensation product; higher proportions ofpolyoxyethylene renders the products solid in consistency. The molecularweights of Pluronic L61, L64 and L68, for example, are approximately2,000, 3,000 and 8,000 respectively.

Examples of other nonionic synthetic detergents useful in the presentinvention are: condensation products of 6 to 30 moles of ethylene oxidewith one mole of an alkyl phenol containing 6 to 12 carbon atoms, eitherin a straight or branched chain, in the alkyl group (e.g., nonyl oroctylphenol); condensation products of 6 to 30 moles of ethyl- .eneoxide with one mole of an aliphatic straight chain or branched chainalcohol containing 8 to 18 carbon atoms (e.g., lauryl alcohol or tallowfatty alcohol); condensation products of ethylene oxide and the reactionproduct of propylene oxide and ethylene diamine wherein the reactionproduct has a molecular weight of 2,5003,000, for example, and thecondensation product has a polyoxyethylene content of 40% to The buildermaterials of the invention are compatible with the usual cleansingcomposition additives and in this connection mention is made of suchcommon adjuncts as bactericidal additives, fillers such as sodiumcarbonate and sodium sulfate, excipients such as sodium stearate andvegetable fats, optical brighteners, anti-redeposition agents such ascarboxymethylcellulose, dyes, pigments, dedusters such as mineral oil,foam stabilizers, tarnish inhibitors, ammonium chloride as 'well as theother known builder materials such as the condensed phosphate, e.g.,tripolyphosphate, pyrophosphates and the like. The builder materialherein also admits the inclusion of bleach agents in the detergent orcleanser compositions such as the chlorinated cyanuric acids,chloramine-T and similar bleaching agents.

Generally speaking, the ratio of detergent surfactant to the builders ofthe invention can vary over wide limits although the usual ratio rangesfrom about 20:1 to about 1:20 where no other builders are present. Whenused in combination with other builder materials such as sodiumtripolyphosphate or in special cleansing formulations, the ratio ofdetergent surfactant to the builders of the invention can vary fromabout 1:100 to about :1.

The diaminoalkanediylidenetetraphosphonic acids herein possess a numberof characteristics which render them excellent materials for use asdetergent builders. One such property is their excellent metalsequestering and chelating ability, the compounds being superior in thisrespect to the builder most commonly used at present, namely, sodiumtripolyphosphate. The metal sequestering abilities of the buildermaterials herein are summarized in Table 1; the chelate stabilityratings in Table 2. Comparison data also are given for sodiumtripolyphosphate and some typical organic builders.

6 bridge, Massachusetts. Magnesium sequestering capacities weredetermined by titration with 0.1 M. magnesium acetate solution to apotentiometric endpoint using a divalent TABLE 1 (RHO P-gCAC(P03HR)sequestering capacity (25 0.,

pH 10) (gram ions metal/mole) RNR RNR A R Ca++ Mg+ Cu Mn++ (A) Compoundsof the invention:

(1) CH2CH2SCH2CH2 H 3. 5 3. 2 2. 1 3. 7 (2) -CH2CH2OCI'I2CH2 H- 3. 2. 1(3) -(OH2)5 H 3. 4 3. 4 2.0 3. 6 (4) -(CH2) H- 2. 9 (CH2)4 HOOH2CH2 1. 7

(B) Compounds of the prior art:

Sodium tripolyphosphate (STPP) 1. 0 1. 2 1. 2 1. 2 Nitrilotn'acetic acid(NTA) 1.0 0. 9 1. 3 2. 7 Aminomethylenediphosphonic acid (AMDP) 1. 5 1.6 1. 2 1. 8 Nitrilotrimethylenephosphonic acid (Dequest) 0.7 0. 9 1.2 1. 5

As Tables 1 and 2 show, the presence of sulfur or oxygen in thealkanediylidene bridge increases the watersolubility of the alkalineearth metal chelates of the tetraphosphonic acids.

Calcium sequestering capacities of the tetraphosphonic acids vary withpH in the range from 9 to 11. Thus, Compound 1 exhibits increasedsequestering capacity as the pH changes from pH 9 to pH 11 whilecompound 3 shows a 3% decrease over the same range. In contrast, thecalcium sequestering capacity of a typical organic builder,aminomethylenediphosphonic acidAMDP-increases by 50% over the pH range 9to 11.

Raising the temperature from C. to 50 C. has little effect on themagnesium sequestering capacity of STPP and AMDP although it increasesthe magnesium sequestering capacity of compound 3 by 14% and thecapacity of compound 1 by 22%.

Calcium and magnesium chelate stabilities of the tetraphosphonic acidscalculated from metal sequestering capacities determined by divalent ionelectrode/oleate indicator methods described elsewhere herein werefound, where measurable, to be sufficiently high to maintain calcium andmagnesium ion concentrations low enough for good detergent building.

ion electrode made by Orion Research, Inc. Cupric copper and manganousmanganese sequestering capacities were determined by titration with 0.1M. cupric sulfate or manganous acetate solution to a visual endpoint.Hydroxyl ion was the precipitant in both instances.

The effectiveness of the compounds herein in reducing calcium andmagnesium ion concentrations is determined by the chelate stabilityconstants of the respective metal ions. The calcium and magnesiumchelate stability constants given in Table 2 were ascertained from themetal ion sequestering capacities using the electrode and oleate methodsand the solubility product of the metal oleate.

(metal chelateY +A l ll l K mstabrhtypK instability=log K instabilitySolubility product of metal oleate 1'7 33 From which [M++] can becalculated given TABLE 2 (RHO P -C-AC(PO3HR) Calcium Magnesium chelatechelate RNR RNR stability stability (pK in- (pK in- A R stability)stability) (A) Compounds of the invention:

(1) CH2CH2SCH2CH2 H (i. 8 6. 3 (2) CHgCH OCH CH2 II- 6.0 6.1 2)s (i) 6.4(4) (CH2)4- H- (1) (5) (CH2)4- HOCHQCH 5.0

(B) Compounds of the prior art:

Sodium tripolyphosphate (SIPP) 5. 4 5. 8 Nitrilotriacetic acid (NTA) 6.2 G. O Aminomethylenediphosphouic acid (AMDP) 5. 9 5. ONitrilotrimethylenephosphonic acid (Dequest) (z) 5. 4

1 Chelate too insoluble to allow measurement. 2 Stability too low tomeasure.

The aminoalkanetetraphosphonic acids are hexabasic, two of the total of8 protons being held by the amino groups forming inner salts. The pKvalues of the fifth electrode chelate capacity-oleate chelate capacityoleate chelate capacity The data of Table 2 show that thealkanediylidenetetraphosphonic acids are capable of maintaining calciumand magnesium ion concentrations lower than is possible with sodiumtripolyphosphate.

Reference is now made to the following non-limiting examples.

Example 1 Adiponitrile (10.8 g., 0.10 mole) and 52.2 g. (0.6 mole) oforthophosphorous acid were charged into a 250 ml., 3-necked,round-bottomed flask fitted with a mechanical stirrer, thermometer,additional funnel and cal cium chloride drying tube. To the mixture wasadded with stirring 111.0 g. (0.41 mole) of phosphorus tribromide over aseven-minute period. An exotherm occurred causing the temperature torise to 44 C. over the next twenty minutes. The reaction temperature wasmaintained at 4550 C. for a total of 4.5 hours by means of a heatingbath. The reaction mixture, which was now a talfy-like mass, was slowlyquenched with 120 ml. of water with stirring resulting in a temperaturerise to 90 C. A white precipitate which formed during the hydrolysis wasseparated by filtration at C., washed with several portions at acetoneand vacuum dried at 100 C. to give 7.0 g. of white solid, M.P. 234262 C.The solid gave a negative test for orthophosphate.

Neutralization Equivalent: 478.Theory is 472. Equivalence points wereobtained at pH 4.1 and 7.9 corresponding to pK values of 2.9, 5.7 and5.7.

Pimelonitrile (36.6 g., 0.30 mole) and 156.6 g. (1.90 moles)orthophosphorous acid were charged into a 500 ml. reactor fitted asdescribed in Example 1. To the mixture was added with stirring 333.0 g.(1.23 moles) of phosphorus tribromide over a seven-minute period. Thereaction mixture was held at 40-50 C. for 7 hours and at 25 C. for 64hours. The reaction mixture was diluted with 165 ml. of Water resultingin a clear solution. Dilution of the solution with 2,000 m1. of acetonecaused the product to precipitate. It was recovered by filtration,'washed with acetone and vacuum dried to give 71.3 g. of crude product.Purification of the crude by dissolution in 10% sodium hydroxide andreprecipitation by acidification with 10% hydrochloric acid gave 29.2 g.of white solid, M.P. 245-257 C.

Neutralization Equivalent: 461.Theory is 450. Equivalence points wereobtained at pH 4.2 and 8.1 corresponding to pK values of 2.9, 5.9 and5.9.

Bis(2-cyanoethyl) sulfide (200 g., 1.43 moles) and 748 g. (9.13 moles)orthophosphorous acid were charged into a 3,000 ml. reactor fitted asdescribed in Example 1. To the mixture was added with stirring 1,580 g.(5.93 moles) of phosphorus tribromide. The reaction mixture was held at50-60 C. for 6 hours and diluted with 600 m1. of water. The resultingclear, yellow solution was vacuum stripped on a rotating evaporator togive a sirup. Dilution of the sirup with 1,000 ml. of denatured ethylalcohol caused a solid to precipitate which was collected on a filter,washed with acetone and vacuum dried to give 384 g. of crude product.The crude product was purified by dissolution in 10% sodium hydroxideand precipitation by acidification with 10% hydrochloric acid. The solidafter separation, washing with acetone and drying weighed 71.3 g., M.P.220239 C.

Neutralization Equivalent: 476.Theory 486. Equivalence points wereobtained at pH 3.8, 7.6 and 10.5 corresponding to pK values of 2.4, 5.6and 9.4.

Bis(Z-cyanoethyl) ether (25 g., 0.20 mole) and g. (1.28 moles)orthophosphorous acid were charged into a 250 ml. reactor fitted asdescribed in Example 1. To the mixture was added with stirring 224 g.(0.82 mole) phosphorous tribromide. The reaction mixture Was held at40-50 C. for 30 hours and at 25 C. for hours. Dilution with 120 ml. ofwater gave a clear yellow solution which was vacuum stripped yielding asirup. The sirup was diluted with 5,000 ml. of acetone to precipitateproduct which was recovered by filtration, Washing with acetone anddrying to give 23.9 g. of white solid, M.P. 127- NeutralizationEquivalent: 450.-Theory 452. Equivalence points were obtained at pH 4.0,7.4 and 10.5, corresponding to pK value of 2.3, 5.8 and 9.1.

Example 5 Detergency tests.The subject materials were tested forbuilding properties and compared with STPP, NTA and AMDP using adetergency test developed by Spangler, Cross and Schaafsma, I. Am. OilChem. Soc., 42, 723 (1955). Test conditions were: Hardness and 300p.p.m.; total detergent concentration 0.15%; temperature 120 F.; pH 9.5.The active material was sodium linear alkylarylsulfonate (Sulframin 85,Ultra Div. Witco Chem. Co.). Detergent formulation compositions were:

Percent by weight Active material 20.0 Sodium metasilicate S-hydrate12.0 Carboxymethyl cellulose (CMC) 0.5 Builder 50.0 Sodium sulfateBalance The tests were run in a Tergotometer on fabric specimens soiledwith a synthetic natural-type soil. The results, given in Table 3 below,are average final percent reflectance readings of fabric specimens after3 soilings and 3 washes. Water of 150 p.p.m. hardness was used forrinsing. Active material to builder ratio was 20/50. The results showthat the tetraphosphonic acids are close to the best of the knownbuilders as represented by STPP, NTA and AMDP in builder eifectivenessunder the conditions used.

l Expressed as percent of sodium tripolyphosphate (STPP) standard.Anionic surfactant; Surfactant/Builder: 20/50 and 20/25; concentration:0.15%; 120 F.; pH 9.5; Hardness, 150 p.p.m. and 300 p.p.m.

From an inspection of the data reported in the tables, it is at onceevident that the alkanediylidenetetraphosphonic acids of the inventionhave several advantages over sodium tripolyphosphate which is thedetergent builder now commonly used. It is particularly significant tonote that the compounds herein are orders of magnitude morehydrolytically stable and thus do not lose their metal sequesteringability over extended periods of time and at elevated temperatures; theyhave a capacity for sequestering calcium which exceeds that of sodiumtripolyphosphate by a factor of 3 on a weight basis (some members arecapable of maintaining the calcium and magnesium ion concentration lowerthan is possible with sodium tripolyphosphate). It is generally believedby those in the art that this is an important factor in detergency;

they exhibit appreciably better sequestering capacity for calcium,magnesium, copper and manganese ions than sodium tripolyphosphate ornitrilotriacetic acid and their calcium and magnesum chelate stabilityconstants generally exceed those of sodium tripolyphosphate ornitrilotriacetic acid.

It is to be understood that the alkanediylidenetetraphosphonic acidbuilders of the invention include and encompass the free acids per se aswell as the ammonium and alkali metal salts as exemplified by theirammonium, trimethylammonium, triethylammonium, dimethylamrnonium,lithium and potassium salts. Those skilled in the art will select thatform of the builder herein which best suits their particular detergentformulation and needs.

Pursuant to the requirements of the patent statutes, the principle ofthis invention has been explained and exemplified in a manner so that itcan be readily practiced by those skilled in the art, suchexemplification including what is considered to represent the bestembodiment of the invention. However, it should be clearly understood,that, within the scope of the appended claims, the invention may bepracticed by those skilled artisans having the benefit of thisdisclosure otherwise than as specifically described and exemplifiedherein.

What is claimed is:

1. A compound of the formula NHz NH;

wherein X is oxygen or sulfur and n is 1 to 3.

2. The compound of claim 1 wherein the formula is 3. The compound ofclaim 1 wherein the formula is FOREIGN PATENTS 1,171,401 6/1964 Germany260-5025 LEON ZITVER, Primary Examiner I. E. EVANS, Assistant ExaminerUS. Cl. X.R.

UMTED STATES PATENT OFFICE CERTEFICATE OF CORRECTION Patent No. 3 5 59"9 Dated February 3, 1971 Inventor(s) Richard Williamson Cummins It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Col. 3, Formula II, that portion of the formula reading (PO3HR)n shouldread (PO HR) Col. 7, Example 3, that portion of the formula reading (POH should read (PO H Col. 7, Example '4, that portion of the formulareading (POZHZ )2 should read (PO HZ 2 G01 8, line 21 "(1955)" shouldread --(l965)-- Col 8, line 57 "acid" should be omitted Col 9, Claim 1that portion of the formula reading {0H) should read (CH Col. 10, Claim3, that portion of the formula reading Should read Signed and sealedthis 18th day of April 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

